I have had 2 AMD x2 550's, and a x2 555 all of which unlocked to X4 quad's and were stable OC'd some. What does AMD benefit from allowing the unlocking, but also what if anything is wrong with the processor for AMD to label it an X2. I usually run intensive games, benchmarks, and some prime to ensure stability... but I can't help think something must be wrong with it for AMD to have bin it as X2.